NF-κB regulates mesenchymal transition for the induction of non-small cell lung cancer initiating cells

PLoS One. 2013 Jul 30;8(7):e68597. doi: 10.1371/journal.pone.0068597. Print 2013.

Abstract

The epithelial-to-mesenchymal transition (EMT) is a de-differentiation process that has been implicated in metastasis and the generation of cancer initiating cells (CICs) in solid tumors. To examine EMT in non-small cell lung cancer (NSCLC), we utilized a three dimensional (3D) cell culture system in which cells were co-stimulated with tumor necrosis factor alpha (TNF) and transforming growth factor beta (TGFβ). NSCLC spheroid cultures display elevated expression of EMT master-switch transcription factors, TWIST1, SNAI1/Snail1, SNAI2/Slug and ZEB2/Sip1, and are highly invasive. Mesenchymal NSCLC cultures show CIC characteristics, displaying elevated expression of transcription factors KLF4, SOX2, POU5F1/Oct4, MYCN, and KIT. As a result, these putative CIC display a cancer "stem-like" phenotype by forming lung metastases under limiting cell dilution. The pleiotropic transcription factor, NF-κB, has been implicated in EMT and metastasis. Thus, we set out to develop a NSCLC model to further characterize the role of NF-κB activation in the development of CICs. Here, we demonstrate that induction of EMT in 3D cultures results in constitutive NF-κB activity. Furthermore, inhibition of NF-κB resulted in the loss of TWIST1, SNAI2, and ZEB2 induction, and a failure of cells to invade and metastasize. Our work indicates that NF-κB is required for NSCLC metastasis, in part, by transcriptionally upregulating master-switch transcription factors required for EMT.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / metabolism*
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Cell Culture Techniques
  • Cell Line, Tumor
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / metabolism*
  • Disease Models, Animal
  • Epithelial-Mesenchymal Transition* / genetics
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Kruppel-Like Factor 4
  • Lung Neoplasms / genetics
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / pathology
  • Mice
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Neoplasm Metastasis
  • Neoplastic Stem Cells / metabolism
  • Phenotype
  • Spheroids, Cellular
  • Tumor Cells, Cultured

Substances

  • KLF4 protein, human
  • Klf4 protein, mouse
  • Kruppel-Like Factor 4
  • NF-kappa B